What are the vital facts about the immunoglobulin G present in the body?
The antibodies, like myeloperoxidase antibody produced from the respective organs in the body, are often called the immunoglobulins. There are different kinds of antibodies produced in response to the presence of the antigens in the body. These antibodies are Y-shaped protein substances that help to neutralize the actions of the different antigens present inside the cells.
Types of antibodies
The different types of antibodies or immunoglobulin present in the body are:
- Immunoglobulin A: This one is found in the saliva, respiratory tract, gut, urogenital tract, and helps in preventing the colonization by the antigens.
- Immunoglobulin E: This one is effective in controlling the harmful effects of the allergens present in the body. It triggers the release of the histamine to fight out the impacts and thereby controls allergic infections in the body..
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- Immunoglobulin G: This one is one of the essential antibodies found in the body, which provides passive immunity to the growing fetus.
- Immunoglobulin D: This one helps in the activation of the basophils and thereby helps in producing antimicrobial factors in the body.
- Immunoglobulin M: This one is expressed on the surface of the monomeric B cells and is used to eliminate the pathogens in the initial stages of the humoral immune responses.
Among all these types of antibodies, let us take a close look at the aspects of the immunoglobulin G:
- Synthesis
Immunoglobulin G is the most common type of antibody secreted by the immune system of the human body. It represents around 75% of the serum antibodies present in humans. This one is released by the plasma B cells and comes with two appropriate antigen-binding sites.
- Structure
IgG antibodies are large globular forms of protein with a molecular weight of around 150kDa. It happens to be formed of 4 peptide chains, which consists of two heavy and two light chains. Thus, this antibody has a tetrameric quaternary structure.
- Functions
The different functions of IgG are:
- The different types of IgG like myeloperoxidase antibody can activate the complement system, which can collectively perforate the cell membranes of the specific antigens present in the body.
- The natural killer cells can express specific member receptors like CD16, which binds actively with the terminal region of the IgG molecule. As these get coated with the IgG antibodies, the natural killer cells can effectively attach themselves with the corresponding antibodies to destroy the targeted antigens.
- IgG is capable of binding to the specific toxins, thereby neutralizing them effectively.
Apart from these aspects, one also must know about the sub-classes of IgG present in the human body. There are typically four sub-classes of IgG, namely IgG1, IgG2, IgG3, and IgG4. These all are secreted by the individual cells depending on the type of antigens present in the cells.